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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Soheil Hassas Yeganeh , Arjun Roy , Eric Dumazet , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: return -ENOMEM for page-table allocation failure in insert_pages() Message-Id: <20260730091558.12e3d9029002c87c1f00b4aa@linux-foundation.org> In-Reply-To: References: <20260730071323.964321-1-thnkslprpt@gmail.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: CEFE6140008 X-Stat-Signature: 4ppaxfjh17tc5dfryj1uyxe5gtepng9c X-Rspam-User: X-HE-Tag: 1785428160-646805 X-HE-Meta: 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 Ny8VLhRx DI9je2TH6eZbypKoKqnC2SjNcdqQH9uwloZyEFKEww70yIfxk3+cncb84MLzcgVIXs9GsDL9Kepkjxd/KaVVIrL1oROw1+eTvehDeIe1DEFjFgb2Vu251jEXwAmy5BqjlbVeBSvckkIknpB+jaWXK2vs0k5PqRLuLs0dioLjbqZm+8WFv9RhydUEbvXk4pqhNLHnt+RF3FpQnQ3Q9GpCIOHs5HtCvr+d+kNvlnDBA0FeN4/0y0h69zYhpzQz66Rol84Du/ByMlqdphqxLg7VOsuhgSM/qcX0kSKxDwD7iHQ5Cn8JaWnEN+mzlH9npAzpnn7en Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, 30 Jul 2026 08:42:49 +0100 "Lorenzo Stoakes (ARM)" wrote: > pages_to_write_in_pmd = min_t(unsigned long, > remaining_pages_total, PTRS_PER_PTE - pte_index(addr)); > > /* Allocate the PTE if necessary; takes PMD lock once only. */ > ret = -ENOMEM; <------------------------------ set it again? > if (pte_alloc(mm, pmd)) > goto out; > > The way this function is written is horrible in general, I hate 'preset default > return value' as a pattern. It used to be the preferred way because ret = -ENOMEM; if (expr) goto out; generated slightly better code than if (expr) { ret = -ENOMEM; goto out; } Whether that is the case with current compilers I don't know.